Symbol: RbAtomic number: 37Atomic mass: 85.4678Group: Alkali Metal

Rubidium is a chemical element in the periodic table that has the symbol Rb and atomic number 37. Rb is a soft, silvery-white metallic element of the alkali metal group

Electronic data

Shells: 2,8,18,8,1Orbitals: [Kr] 5s1

Electronegativity: 0.9, 0.81. Ionization potential: 4.1771 eV2. Ionization potential: 27.28 eV3. Ionization potential: 40.0 eVOxidation states: 1Electrical conductivity: 0.0779 10^6

Thermal data

Melting point: 38.89 °C Boiling point: 686 °C Specific heat: 0.363 J/gKHeat of fusion: 2.192 kJ/molHeat of vaporization: 72.216 kJ/molThermal conductivity: 0.582 W/cmK

Steric Data

Atomic radius: 2.98 ÅIonic radius: 1.61 Å ()Covalent radius: 2.16 ÅAtomic volume: 55.9 cm³/molDensity (293 K): 1.53 g/cm³Crystal structure: Cubic: Body centered

HistoryHistory Rubidium was discovered Rubidium was discovered

by the German chemists by the German chemists Robert Bunsen and Gustav Robert Bunsen and Gustav Kirchoff in 1861 while Kirchoff in 1861 while analyzing samples of the analyzing samples of the mineral lepidolite mineral lepidolite (KLi(KLi22Al(Al, Si)Al(Al, Si)33OO1010(F, OH)(F, OH)22) ) with a device called a with a device called a spectroscope. The sample spectroscope. The sample produced a set of deep produced a set of deep red spectral lines they had red spectral lines they had never seen before never seen before

The name rubidium (from The name rubidium (from the Latin "rubidus" - dark the Latin "rubidus" - dark red) was coined for its red) was coined for its bright red spectroscopic bright red spectroscopic lines.lines.

Bunsen

Kirchoff

OccurrenceOccurrence

This element is considered to be the 16th most This element is considered to be the 16th most abundant element in the abundant element in the earthearth's crust. 's crust.

It occurs naturally in the minerals It occurs naturally in the minerals leuciteleucite, , pollucitepollucite, and , and zinnwalditezinnwaldite, which contains traces of up to , which contains traces of up to 1% of its 1% of its oxideoxide. . LepidoliteLepidolite contains 1.5% rubidium contains 1.5% rubidium and this is the commercial source of the element. and this is the commercial source of the element.

Some Some potassiumpotassium minerals and minerals and potassium chloridespotassium chlorides also contain the element in commercially also contain the element in commercially significant amounts. One notable source is also in significant amounts. One notable source is also in the extensive deposits of the extensive deposits of pollucitepollucite at at Bernic LakeBernic Lake, , ManitobaManitoba. Rubidium metal can be produced by . Rubidium metal can be produced by reducingreducing rubidium chloride with rubidium chloride with calciumcalcium among among other methods. other methods.

IsolationIsolation Rubidium would not normally be made in the laboratory as Rubidium would not normally be made in the laboratory as

it is available commercially. All syntheses require an it is available commercially. All syntheses require an electrolytic step as it is so difficult to add an electron to the electrolytic step as it is so difficult to add an electron to the poorly electronegative rubidium ion Rb+. poorly electronegative rubidium ion Rb+.

Rubidium is not made by the same method as sodium as Rubidium is not made by the same method as sodium as might have been expected. This is because the rubidium might have been expected. This is because the rubidium metal, once formed by electrolysis of liquid rubidium metal, once formed by electrolysis of liquid rubidium chloride (RbCl), is too soluble in the molten salt.chloride (RbCl), is too soluble in the molten salt.cathode: Rb+(l) + e- Rb (l) anode: Cl-(l) 1/2Cl2 (g) + e-cathode: Rb+(l) + e- Rb (l) anode: Cl-(l) 1/2Cl2 (g) + e-

Instead, it is made by the reaction of metallic sodium with Instead, it is made by the reaction of metallic sodium with hot molten rubidium chloride.hot molten rubidium chloride.Na + RbCl Rb + NaClNa + RbCl Rb + NaClThis is an equilibrium reaction and under these conditions This is an equilibrium reaction and under these conditions the rubidium is highly volatile and removed from the the rubidium is highly volatile and removed from the system in a form relatively free from sodium impurities, system in a form relatively free from sodium impurities, allowing the reaction to proceed.allowing the reaction to proceed.

Chemical reactions of the Chemical reactions of the elementselements

Reaction of rubidium with airReaction of rubidium with airIf rubidium is burned in air, the result is mainly If rubidium is burned in air, the result is mainly formation of dark brown rubidium superoxide, formation of dark brown rubidium superoxide, RbORbO22..

Rb(s) + ORb(s) + O22(g) RbO(g) RbO22(s)(s)

Reaction of rubidium with waterReaction of rubidium with waterRubidium metal reacts very rapidly with water to Rubidium metal reacts very rapidly with water to form a colourless solution of rubidium hydroxide form a colourless solution of rubidium hydroxide (RbOH) and hydrogen gas (H(RbOH) and hydrogen gas (H22). The reaction is ). The reaction is very exothermic. very exothermic.

2 Rb(s) + 2H2 Rb(s) + 2H22O 2RbOH(aq) + HO 2RbOH(aq) + H22(g)(g)

Chemical reactions of the Chemical reactions of the elementselements

Reaction of rubidium with the halogensReaction of rubidium with the halogensRubidium metal reacts vigorously with all the Rubidium metal reacts vigorously with all the halogens to form rubidium halides.halogens to form rubidium halides.2Rb(s) + F2Rb(s) + F22(g) RbF(s)(g) RbF(s)2Rb(s) + Cl2Rb(s) + Cl22(g) RbCl(s)(g) RbCl(s)2Rb(s) + Br2Rb(s) + Br22(g) RbBr(s)(g) RbBr(s)2Rb(s) + I2Rb(s) + I22(g) RbI(s)(g) RbI(s)

Reaction of rubidium with acidsReaction of rubidium with acidsRubidium metal dissolves readily in dilute Rubidium metal dissolves readily in dilute sulphuric acid to form solutions containing the sulphuric acid to form solutions containing the aquated Rb(I) ion together with hydrogen gas, Haquated Rb(I) ion together with hydrogen gas, H22..2Rb(s) + H2Rb(s) + H22SOSO44(aq) 2Rb(aq) 2Rb++(aq) + SO(aq) + SO44

2-2-(aq) + (aq) + HH22(g)(g)

Binary Compounds Binary Compounds

HydridesHydrides

HRbHRb: rubidium (I) hydride : rubidium (I) hydride FluoridesFluorides

RbFRbF: rubidium (I) fluoride : rubidium (I) fluoride ChloridesChlorides

RbClRbCl: rubidium (I) chloride : rubidium (I) chloride BromidesBromides

RbBrRbBr: rubidium (I) bromide : rubidium (I) bromide IodidesIodides

RbIRbI: rubidium (I) iodide : rubidium (I) iodide

SulfidesSulfides

RbRb22SS: rubidium (I) sulphide: rubidium (I) sulphide SelenidesSelenides

RbRb22SeSe: rubidium (I) selenide : rubidium (I) selenide TelluridesTellurides

RbRb22TeTe: rubidium (I) telluride : rubidium (I) telluride OxidesOxides

RbRb22OO: rubidium (I) oxide : rubidium (I) oxide

RbORbO22: rubidium (I) : rubidium (I) superoxide superoxide

RbRb22OO22: rubidium (I) peroxide: rubidium (I) peroxide

ApplicationsApplications Rubidium is easily ionized, and so has Rubidium is easily ionized, and so has

possible use in "ion engines" for space possible use in "ion engines" for space vehicles vehicles

As a getter in vacuum tubes. As a getter in vacuum tubes. As a photocell component. As a photocell component. In the making of special glasses. In the making of special glasses. Rubidium compounds are sometimes used Rubidium compounds are sometimes used

in fireworks to give them a purple colorin fireworks to give them a purple color. .